Definition: This vestige of a pre-historic toe sits on the inside of the cannon bone a few inches above the knee. It is made up of very soft hoof-like material and grows slowly. On some horses the growth flakes off naturally. If the chestnut looks like it is getting long it is perfectly safe to pull off the dead growth. It will likely peel away to almost skin level.
Examples: Before the show we trimmed back the chestnut to neaten it.